1. Field of the Invention
Exemplary embodiments of the present invention relate to a method of inspecting a substrate or, more particularly, to a method of inspecting a substrate capable of enhancing reliability of a process of inspecting a status of an element mounted on a substrate.
2. Discussion of the Background
In general, an inspection process is required to inspect reliability of a substrate with an electronic device mounted thereon before and after the electronic device is mounted on the substrate. For example, a pad area of a substrate is inspected in order to inspect a status of solder for mounting an electronic device onto the substrate, before the electronic device is mounted on the substrate, and the status of the electronic device is inspected if the electronic device is properly mounted after the electronic device is mounted on the substrate.
Recently, a method of inspecting a substrate has been used for inspecting three dimensional shape of a target object by using an apparatus of inspecting three dimensional shape, which includes a plurality of projecting parts, each of which includes a light source and a grating to project pattern light onto the target object, and a camera capturing an image of the target object.
In order to inspect the three dimensional shape of the target object, height data of the target object is required. The height of the target object is calculated by setting up a ground area of the substrate to be a reference. However, the ground area of the substrate includes noise, so that it is hard to obtain reliable height data. Furthermore, in some cases, a plurality of target objects are disposed densely, so an amount of data of a ground area may be insufficient, or the amount of data of the ground area may be insufficient due to a shadow area. Especially, when the target object is an electronic device with height, a shadow may be generated due to the electronic device, to make amount of data of the ground area, which is reliable, insufficient. As a result, reliability of height of the target object is lowered.